1dnl Available from the GNU Autoconf Macro Archive at:
2dnl http://www.gnu.org/software/ac-archive/htmldoc/acx_pthread.html
3dnl
4AC_DEFUN([ACX_PTHREAD], [
5AC_REQUIRE([AC_CANONICAL_HOST])
6AC_LANG_SAVE
7AC_LANG_C
8acx_pthread_ok=no
9
10# We used to check for pthread.h first, but this fails if pthread.h
11# requires special compiler flags (e.g. on True64 or Sequent).
12# It gets checked for in the link test anyway.
13
14# First of all, check if the user has set any of the PTHREAD_LIBS,
15# etcetera environment variables, and if threads linking works using
16# them:
17if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
18        save_CFLAGS="$CFLAGS"
19        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
20        save_LIBS="$LIBS"
21        LIBS="$PTHREAD_LIBS $LIBS"
22        AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
23        AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
24        AC_MSG_RESULT($acx_pthread_ok)
25        if test x"$acx_pthread_ok" = xno; then
26                PTHREAD_LIBS=""
27                PTHREAD_CFLAGS=""
28        fi
29        LIBS="$save_LIBS"
30        CFLAGS="$save_CFLAGS"
31fi
32
33# We must check for the threads library under a number of different
34# names; the ordering is very important because some systems
35# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
36# libraries is broken (non-POSIX).
37
38# Create a list of thread flags to try.  Items starting with a "-" are
39# C compiler flags, and other items are library names, except for "none"
40# which indicates that we try without any flags at all.
41
42acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt"
43
44# The ordering *is* (sometimes) important.  Some notes on the
45# individual items follow:
46
47# pthreads: AIX (must check this before -lpthread)
48# none: in case threads are in libc; should be tried before -Kthread and
49#       other compiler flags to prevent continual compiler warnings
50# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
51# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
52# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
53# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
54# -pthreads: Solaris/gcc
55# -mthreads: Mingw32/gcc, Lynx/gcc
56# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
57#      doesn't hurt to check since this sometimes defines pthreads too;
58#      also defines -D_REENTRANT)
59# pthread: Linux, etcetera
60# --thread-safe: KAI C++
61
62case "${host_cpu}-${host_os}" in
63        *solaris*)
64
65        # On Solaris (at least, for some versions), libc contains stubbed
66        # (non-functional) versions of the pthreads routines, so link-based
67        # tests will erroneously succeed.  (We need to link with -pthread or
68        # -lpthread.)  (The stubs are missing pthread_cleanup_push, or rather
69        # a function called by this macro, so we could check for that, but
70        # who knows whether they'll stub that too in a future libc.)  So,
71        # we'll just look for -pthreads and -lpthread first:
72
73        acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
74        ;;
75esac
76
77if test x"$acx_pthread_ok" = xno; then
78for flag in $acx_pthread_flags; do
79
80        case $flag in
81                none)
82                AC_MSG_CHECKING([whether pthreads work without any flags])
83                ;;
84
85                -*)
86                AC_MSG_CHECKING([whether pthreads work with $flag])
87                PTHREAD_CFLAGS="$flag"
88                ;;
89
90                *)
91                AC_MSG_CHECKING([for the pthreads library -l$flag])
92                PTHREAD_LIBS="-l$flag"
93                ;;
94        esac
95
96        save_LIBS="$LIBS"
97        save_CFLAGS="$CFLAGS"
98        LIBS="$PTHREAD_LIBS $LIBS"
99        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
100
101        # Check for various functions.  We must include pthread.h,
102        # since some functions may be macros.  (On the Sequent, we
103        # need a special flag -Kthread to make this header compile.)
104        # We check for pthread_join because it is in -lpthread on IRIX
105        # while pthread_create is in libc.  We check for pthread_attr_init
106        # due to DEC craziness with -lpthreads.  We check for
107        # pthread_cleanup_push because it is one of the few pthread
108        # functions on Solaris that doesn't have a non-functional libc stub.
109        # We try pthread_create on general principles.
110        AC_TRY_LINK([#include <pthread.h>],
111                    [pthread_t th; pthread_join(th, 0);
112                     pthread_attr_init(0); pthread_cleanup_push(0, 0);
113                     pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
114                    [acx_pthread_ok=yes])
115
116        LIBS="$save_LIBS"
117        CFLAGS="$save_CFLAGS"
118
119        AC_MSG_RESULT($acx_pthread_ok)
120        if test "x$acx_pthread_ok" = xyes; then
121                break;
122        fi
123
124        PTHREAD_LIBS=""
125        PTHREAD_CFLAGS=""
126done
127fi
128
129# Various other checks:
130if test "x$acx_pthread_ok" = xyes; then
131        save_LIBS="$LIBS"
132        LIBS="$PTHREAD_LIBS $LIBS"
133        save_CFLAGS="$CFLAGS"
134        CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
135
136        # Detect AIX lossage: threads are created detached by default
137        # and the JOINABLE attribute has a nonstandard name (UNDETACHED).
138        AC_MSG_CHECKING([for joinable pthread attribute])
139        AC_TRY_LINK([#include <pthread.h>],
140                    [int attr=PTHREAD_CREATE_JOINABLE;],
141                    ok=PTHREAD_CREATE_JOINABLE, ok=unknown)
142        if test x"$ok" = xunknown; then
143                AC_TRY_LINK([#include <pthread.h>],
144                            [int attr=PTHREAD_CREATE_UNDETACHED;],
145                            ok=PTHREAD_CREATE_UNDETACHED, ok=unknown)
146        fi
147        if test x"$ok" != xPTHREAD_CREATE_JOINABLE; then
148                AC_DEFINE(PTHREAD_CREATE_JOINABLE, $ok,
149                          [Define to the necessary symbol if this constant
150                           uses a non-standard name on your system.])
151        fi
152        AC_MSG_RESULT(${ok})
153        if test x"$ok" = xunknown; then
154                AC_MSG_WARN([we do not know how to create joinable pthreads])
155        fi
156
157        AC_MSG_CHECKING([if more special flags are required for pthreads])
158        flag=no
159        case "${host_cpu}-${host_os}" in
160                *-aix* | *-freebsd*)     flag="-D_THREAD_SAFE";;
161                *solaris* | *-osf* | *-hpux*) flag="-D_REENTRANT";;
162        esac
163        AC_MSG_RESULT(${flag})
164        if test "x$flag" != xno; then
165                PTHREAD_CFLAGS="$flag $PTHREAD_CFLAGS"
166        fi
167
168        LIBS="$save_LIBS"
169        CFLAGS="$save_CFLAGS"
170
171        # More AIX lossage: must compile with cc_r
172        AC_CHECK_PROG(PTHREAD_CC, cc_r, cc_r, ${CC})
173else
174        PTHREAD_CC="$CC"
175fi
176
177AC_SUBST(PTHREAD_LIBS)
178AC_SUBST(PTHREAD_CFLAGS)
179AC_SUBST(PTHREAD_CC)
180
181# Finally, execute ACTION-IF-FOUND/ACTION-IF-NOT-FOUND:
182if test x"$acx_pthread_ok" = xyes; then
183        ifelse([$1],,AC_DEFINE(HAVE_PTHREAD,1,[Define if you have POSIX threads libraries and header files.]),[$1])
184        :
185else
186        acx_pthread_ok=no
187        $2
188fi
189AC_LANG_RESTORE
190])dnl ACX_PTHREAD
191